With the continuous development of the broadband wireless communication technology, some next-generation broadband mobile communication systems such as Worldwide Interoperability for mobile Microwave Access (WiMAX), Ultra Mobile Broadband (UMB), 3GPP Long Term Evolution (LTE) and so on adopt a multiple access manner of the Orthogonal Frequency Division Multiple Access (OFDMA) in the downlink. In a given system bandwidth, and from the point view of the frequency domain, different users can achieve multiple access by occupying a certain amount of orthogonal sub-carrier resources.
The mapping manner of sub-carriers in the frequency domain can be classified into a localized mapping manner and a distributed mapping manner. In the original OFDMA system, all the sub-carriers on the frequency domain usually use one of the localized mapping manner and the distributed mapping manner on the same OFDM symbol. In the above, the sub-carrier resources in the resource block allocated to the user in the localized sub-carrier mapping manner are continuous; and the sub-carrier resources in the resource block allocated to the user in the distributed sub-carrier mapping manner are discrete, since it is needed to permute all the sub-carriers in the range of a frequency band through a permutation sequence in the distributed sub-carrier mapping manner. From the point of view of functions, the localized mapping manner can support a frequency selective scheduling, while the distributed mapping manner can generate the frequency diversity. Therefore, in the next-generation broadband wireless access system, the sub-carriers on the frequency domain will use a resource mapping manner of hybrid mapping of both the localized and the distributed mapping manners on the same OFDM symbol, so as to satisfy the requirements on the quality of service (QoS) of different services by different users.
In the evolution of an OFDMA multiple access system, in order to reduce the shared-frequency interference between cells, a partial frequency multiplexing technology is adopted, in which different frequency partitions respectively occupy certain sub-carrier resources. In the downlink of the OFDMA system using the partial frequency multiplexing technology, it is a trend of the development of the next-generation broadband wireless communication technology that combining the localized mapping and the distributed mapping with the partial frequency multiplexing technology. By making use of a two-level sub-carrier mapping manner, which consists of an external mapping based on the sub-carriers of the whole frequency band and an internal mapping based on the sub-carriers within the frequency partition, it is beneficial to use the advantages of both the localized mapping and the distributed mapping simultaneously, and realize the combination of the two kinds of mapping manners with the partial frequency multiplexing technology. In the above, the external mapping is executed aiming at the sub-carrier resources of the whole system frequency band, and maps the corresponding sub-carrier resources into each frequency partition; and the internal mapping is executed based on the sub-carrier resources within each frequency partition. However, currently, under the two-level sub-carrier mapping manner, there is no effective external mapping manner which is able to divide the sub-carrier resources and allocate the divided sub-carrier resources to each frequency partition flexibly according to the system configuration.